Happy Dom CVEs and Security Vulnerabilities

CVE-2026-34226

Happy DOM's fetch credentials include uses page-origin cookies instead of target-origin cookies

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Versions prior to 20.8.9 may attach cookies from the current page origin (`window.location`) instead of the request target URL when `fetch(..., { credentials: "include" })` is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Capricorn86

Products

Happy-dom Happy Dom

CVE-2026-33943

Happy DOM ECMAScriptModuleCompiler: unsanitized export names are interpolated as executable code

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. In versions 15.10.0 through 20.8.7, a code injection vulnerability in `ECMAScriptModuleCompiler` allows an attacker to achieve Remote Code Execution (RCE) by injecting arbitrary JavaScript expressions inside `export { }` declarations in ES module scripts processed by happy-dom. The compiler directly interpolates unsanitized content into generated code as an executable expression, and the quote filter does not strip backticks, allowing template literal-based payloads to bypass sanitization. Version 20.8.8 fixes the issue.

CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed